Introduction
- Inherited retinal degeneration seen in Abyssinian; early and late form generalized retinal degeneration, late-onset suspected in Siamese.
- Also seen in some Domestic Shorthaired cats, etiology unknown.
- Feline Central Retinal Degeneration (FCRD) associated with taurine deficiency
. - Signs : visual deficit especially at night, nervousness with other animals, may be no obvious clinical signs, pupil dilation and increased tapetal reflex visible through pupil.
- Diagnosis : ophthalmic examination, electroretinography, blood taurine assay.
- Treatment : dependent on cause.
- Prognosis : most degenerations are progressive unless predisposing factors can be treated. Pet cats usually cope well with blindness.
Diagnosis
Clinical signs
FPRD- Poor pupillary reflexes.
- Reduced response to menacing gestures.
- Inability to negotiate a maze, especially in low light conditions.
- Retinal signs include:
- Peripapillary discoloration
(suspected disease). - Tapetal color changes with early vascular attenuation (early disease).
- Tapetal hyperreflectivity with obvious vascular changes (moderately advanced disease).
- Total tapetal hyperreflectivity with minimal to no vasculature evident and a gray, atrophic optic disc (end stage disease).
- Peripapillary discoloration
FCRD
- Early signs is increased granularity of area centralis, followed by a typical elliptical hyperreflective lesion in the area centralis (dorso-lateral to the optic disc).
- A second hyperreflective zone nasal to the optic disc develops .
- Elongation of the two zones occurs → confluent .
- End stage is total retinal hyperreflectivity .
- Blindness not seen until almost the end stage of the disease.
Diagnosis
Differential diagnosis
- Differentiate late stage disease from other causes of retinal disease, including inflammation of the posterior segments, eg:
- Viral.
- Bacterial.
- Protozoal.
- Fungal.
- Parasitic.
- Neoplastic.
- Toxic.
- Immune mediated.
- Many of the above show focal or multifocal retinal degenerative lesions.
- Retinal detachment with subsequent reattachment.
- Glaucoma .
- Mucopolysaccharidosis : cats show normal morphology, but with some behavioral signs of retinal degeneration as well as other neurological deficits.
Sequelae
Prognosis
FPRD- Progressive disease - no treatment.
- Pet cats usually cope well with blindness.
FCRD
- Good, if disease caught early enough and treatment is successful.
Sources
Publications
Refereed papers
- Millichamp N J (1990)Retinal degeneration in the dog and cat.Vet Clin NA Small Anim Pract.20(3), 799-835.
- Narfstrom K (1985)Progressive retinal atrophy in the Abyssinian cat - clinical characteristics.Invest Ophthalmol Vis Sci26, 193-200.
Other sources of information
- Nasisse M P (1991)Feline ophthalmology.In:Veterinary Ophthalmology, 2nd edn.Gelatt K Npp529-575. Philadelphia: Lea and Febiger.
- Petersen-Jones S & Crispin S (2002)BSAVA Manual of Small Animal Ophthalmology.2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4
